How long will the air conditioner last if it is making a loud squealing noise. I want to know if I have to replace it right away.
Usually it will either be the belt is slipping on the AC pulley because the serpentine belt is worn out, the tensioner pulley is no longer providing the amount of tension on the serpentine belt, or the belt needs adjustment. You can try belt replacement first or check the tensioner to see if it is where it should be (a lot of them have a gauge to show where the proper range should be). If it isn't, then you can either change out the tensioner (the springed portion) or the belt depending if you found fault in one of those areas. If that doesn't work, then there may be an issue with the AC itself. More than likely, the AC is not at fault and it will work just fine after the belt/tensioner is replaced.
Check what Paulster2 said and if that doesn't fix the problem it could be the bearings in the AC clutch..... spray some WD-40 in there and if the problem lessens, then it's a good sign the clutch needs replacement. The WD-40 won't be a fix. Good luck.